Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:55794 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751996AbbATOgr (ORCPT ); Tue, 20 Jan 2015 09:36:47 -0500 Date: Tue, 20 Jan 2015 09:36:45 -0500 From: Bruce Fields To: Junxiao Bi Cc: Jeff Layton , Trond Myklebust , Linux NFS Mailing List Subject: Re: [PATCH] nfsd: fix memory corruption due to uninitialized variable Message-ID: <20150120143645.GB7899@fieldses.org> References: <1421584142-12505-1-git-send-email-junxiao.bi@oracle.com> <54BC5B3F.9080004@oracle.com> <20150119092953.2584b496@tlielax.poochiereds.net> <54BE40DB.4070801@oracle.com> <20150120072359.70053ddf@tlielax.poochiereds.net> <54BE4992.4060805@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <54BE4992.4060805@oracle.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, Jan 20, 2015 at 08:26:58PM +0800, Junxiao Bi wrote: > On 01/20/2015 08:23 PM, Jeff Layton wrote: > >On Tue, 20 Jan 2015 19:49:47 +0800 > >Junxiao Bi wrote: > > > >>On 01/19/2015 10:29 PM, Jeff Layton wrote: > >>>On Mon, 19 Jan 2015 09:17:51 +0800 > >>>Junxiao Bi wrote: > >>>>Yes, we got the following panic from 3.8.13. The bad pointer > >>>>open->op_stp was freed into kmem_cache array_cache, and was allocated to > >>>>next "op_stp" allocation request which triggered the panic. > >>>> > >>>> > >>>>@ PID: 21663 TASK: ffff8809fe6103c0 CPU: 0 COMMAND: "nfsd" > >>>>@ #0 [ffff8809fe613980] machine_kexec at ffffffff810421d9 > >>>>@ #1 [ffff8809fe6139f0] crash_kexec at ffffffff810c9d39 > >>>>@ #2 [ffff8809fe613ac0] oops_end at ffffffff81599298 > >>>>@ #3 [ffff8809fe613af0] die at ffffffff8101870b > >>>>@ #4 [ffff8809fe613b20] do_general_protection at ffffffff8159906c > >>>>@ #5 [ffff8809fe613b50] general_protection at ffffffff81598668 > >>>>@ [exception RIP: init_stid+14] > >>>>@ RIP: ffffffffa058247e RSP: ffff8809fe613c08 RFLAGS: 00010292 > >>>>@ RAX: 0000000000000000 RBX: 736e61727465722c RCX: 0000000000000000 > >>>>@ RDX: 0000000000000001 RSI: ffff8808e433a800 RDI: 736e61727465722c > >>>>@ RBP: ffff8809fe613c28 R8: ffff880a01469000 R9: 0000000000000000 > >>>>@ R10: 0000000000000000 R11: 0000000000000000 R12: ffff8808e19821a0 > >>>>@ R13: ffff8809aa40f3a8 R14: ffff8809fd781040 R15: ffff8809aafc9c98 > >>>>@ ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 > >>>>@ #6 [ffff8809fe613c30] nfsd4_process_open2 at ffffffffa0588123 [nfsd] > >>>>@ #7 [ffff8809fe613d00] nfsd4_open at ffffffffa0577e82 [nfsd] > >>>>@ #8 [ffff8809fe613d50] nfsd4_proc_compound at ffffffffa0575de8 [nfsd] > >>>>@ #9 [ffff8809fe613db0] nfsd_dispatch at ffffffffa056429b [nfsd] > >>>>@ #10 [ffff8809fe613df0] svc_process_common at ffffffffa04afd14 [sunrpc] > >>>>@ #11 [ffff8809fe613e70] svc_process at ffffffffa04b034f [sunrpc] > >>>>@ #12 [ffff8809fe613e90] nfsd at ffffffffa05649ff [nfsd] > >>>>@ #13 [ffff8809fe613ec0] kthread at ffffffff81082f4e > >>>>@ #14 [ffff8809fe613f50] ret_from_fork at ffffffff815a09ac ... > >>Found the cause, this issue should have been fix by the following > >>commit. This fix is not merged in 3.8.13. Thanks for you and Trond > >>review it. Oh, sorry for not thinking of that one.... I wonder how you hit this case--which client were you using? --b. > >> > >>commit 5d6031ca742f9f07b9c9d9322538619f3bd155ac > >>Author: J. Bruce Fields > >>Date: Thu Jul 17 16:20:39 2014 -0400 > >> > >> nfsd4: zero op arguments beyond the 8th compound op > >> > >> The first 8 ops of the compound are zeroed since they're a part of the > >> argument that's zeroed by the > >> > >> memset(rqstp->rq_argp, 0, procp->pc_argsize); > >> > >> in svc_process_common(). But we handle larger compounds by allocating > >> the memory on the fly in nfsd4_decode_compound(). Other than code > >> recently fixed by 01529e3f8179 "NFSD: Fix memory leak in encoding > >>denied > >> lock", I don't know of any examples of code depending on this > >> initialization. But it definitely seems possible, and I'd rather be > >> safe. > >> > >> Compounds this long are unusual so I'm much more worried about failure > >> in this poorly tested cases than about an insignificant performance > >>hit. > >> > >> Signed-off-by: J. Bruce Fields > >> > >>diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > >>index 01023a5..628b430 100644 > >>--- a/fs/nfsd/nfs4xdr.c > >>+++ b/fs/nfsd/nfs4xdr.c > >>@@ -1635,7 +1635,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp) > >> goto xdr_error; > >> > >> if (argp->opcnt > ARRAY_SIZE(argp->iops)) { > >>- argp->ops = kmalloc(argp->opcnt * sizeof(*argp->ops), > >>GFP_KERNEL); > >>+ argp->ops = kzalloc(argp->opcnt * sizeof(*argp->ops), > >>GFP_KERNEL); > >> if (!argp->ops) { > >> argp->ops = argp->iops; > >> dprintk("nfsd: couldn't allocate room for > >>COMPOUND\n"); > >> > >>Thanks, > >>Junxiao. > >Yes, that patch looks fine, and I'm pretty sure it'd be ok for stable. > yes. > >I don't think v3.8 is being maintained anymore though, is it? > Used by us internal. > > Thanks, > Junxiao. > > >